import java.util.*;
public class Main
{
    public static void main(String[] args)
    {
      Scanner sc=new Scanner(System.in);
      int n=sc.nextInt();
      if(!sc.hasNextInt())
      {
           System.out.println("Invaild input"); 
      }
      if(n<=0)
      {
          System.out.println("Invaild input"); 
      }
      int [] arr=new int [n];
      int cnt=0;
        for(int i=0;i<n;i++)
        {
            if(sc.hasNextInt())
            {
            arr[i]=sc.nextInt();
            cnt++;
            }
            else
            {
                System.out.print("Invalid input");
                return;
            }
        }
        int c=0;

      if(cnt!=n)
      {
          System.out.print("Ïnvalid input");
      }
        for(int i=0;i<arr.length();i++)
        {
            for(int j=i+1;j<arr.length();j++)
            {
                if(arr[i]==arr[j])
                {
                System.out.println(arr[i]);
                c=1;
                }
            }
          
        }
          
         if(c==0)
         {
            System.out.println("No duplicates found");   
         }
       
    }
}